Objective: In Japan, there had been no prospective clinical studies conducted in terms of modified FOLFOX6 + bevacizumab therapy. We performed a post-marketing Phase II multicenter clinical study to examine the efficacy and safety of this regimen as first-line therapy for Japanese patients with advanced/recurrent colorectal cancer. Methods: Bevacizumab (5 mg/kg) was administered intravenously, and then oxaliplatin (85 mg/m2) and levofolinate calcium (200 mg/m2) were infused intravenously over 2 h. Subsequently, a bolus dose of 5-fluorouracil (400 mg/m2) was injected, followed by infusion of 5-fluorouracil (2400 mg/m2) for 46 h. This regimen was repeated every 2 weeks until 24 cycles unless there was disease progression, unacceptable toxicity or patient refusal. The primary end point was the response rate. Results: Among the 70 patients enrolled, two patients withdrew the study before treatment, and 68 patients were eligible for analysis of efficacy and safety. The response rate was 51.5% (95% confidence interval: 39.0–63.8%). The median progression-free survival and median overall survival time were 12.6 months (95% confidence interval: 10.4–14.5 months) and 28.5 months [95% confidence interval: 23.1 months–(not applicable)], respectively. There were no treatment-related deaths observed. The most common Grade 3 and 4 adverse events included neutropenia in 35.3% of the patients, peripheral neuropathy in 16.2% and hypertension in 16.2%. All adverse events were manageable and tolerable. The exploratory analysis of polymorphisms of three genes, ERCC1, XPD and GSTP1, did not show any trends in terms of correlation with the efficacy or safety of modified FOLFOX6 + bevacizumab therapy. Conclusions: Modified FOLFOX6 + bevacizumab therapy was manageable and tolerable in Japanese patients, achieving a high response rate.